Single-Walled Carbon Nanotube Separations Using Simple Metal Ionic Salt Additives in Gel-Based Chromatography

Abstract

Metal ionic salts, MXn (M = Li, Na, K, Mg, Ca, and Ba; X = Cl, I, and SCN; n = 1 or 2), are found to affect elution of adsorbed semiconducting single-walled carbon nanotubes (S-SWCNTs) in a gel-based chromatographic column. The process is dramatically affected by the change in metal cation, with little effect resulting from modification of salt anion. The elution is shown to follow a logarithmic relationship between the metal ion size and the salt concentration used to achieve optimal separation. Alkaline earth ions yielded optimal S-SWCNT elutions at concentrations as low as ∼10 mM. Importantly, the method described dramatically reduces material additive costs (< $1 / L) needed for large scale amounts of electronically pure SWCNTs.